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STOP
PLUTONIUM
Le
Plutonium
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PLUTONIUM
- Pu
Description
: artificial heavy metal
Isotopes
: fifteen isotopes including plutonium 238, 239, and 241
Production
: irradiation of uranium 238
Use
:
plutonium 239 => nuclear warhead and MOX fuel component;
plutonium 238 => source of neutrons and heat
Radioactivity
: alpha particle and low-level gamma ray emitter, except
in the case of plutonium 241 beta emitter
Note
: plutonium 239 and 241 are fissile materials. Plutonium
is a heavy metal that exists only at traces levels in the
natural environment. Almost all plutonium in existence has
been man made in the twentieth century.
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There are fifteen
known plutonium isotopes. Those relevant to plutonium use are plutonium
238, 239, 240, 241 and 242. All are radioactive and described as fissile.
Plutonium 239 and 241 are equally fissile; however it is plutonium 239
that is generally used for energy and weapon production. Plutonium 241
is rarely used separately due to difficulties associated with its large-scale
production, an elevated production cost, a short half-life, and a greater
radioactivity than that of plutonium 239. Plutonium 238 has commercial
and military applications because it is an exceptionally alpha ray strong
emitter. Plutonium 240 and 242 are merely neutron poisons.
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SQUARE 94
Plutonium is a high density grey metal. It occupies square 94 of
the Periodic Table of chemical elements, as its nucleus contains
94 protons. It is an artificial element, discovered in 1941 by Glen
Seaborg, who was awarded the chemistry Nobel Prize in 1951. Plutonium
can exist in various forms, called isotopes, characterised by the
number of neutrons in the nucleus (in addition to the 94 protons).
Thus, isotope 232, the lightest isotope, contains 138 neutrons.
Isotope 246 is the heaviest with 152 neutrons. All the isotopes
are radioactive, but their life spans differ: 87,7 years for plutonium
238, 379 000 years for plutonium 242.
Plutonium
is created within enriched uranium. When uranium 238 captures a
neutron emitted by nuclear fission, it is transformed into uranium
239. This unstable isotope then, in a few minutes, transmutes itself
into neptunium 239. Two days later, neptunium 239 becomes plutonium
239
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